Adherence to recommendations to wait until 6 months to introduce solid foods into infants' diets is very poor. An in-depth understanding of the factors involved in this decision is essential if health practitioners are to offer suitable advice and health education. A cross-sectional electronic questionnaire study was conducted with 105 mothers recruited via UK-based Internet parenting discussion forums. Ratings of variables important in making the decision to introduce solid foods were analyzed using factor analysis and multiple regression. Open-ended questions were analyzed qualitatively using content analysis. In this sample of educated women, later weaning was found to be associated with a focus on the importance of the recommendations and a perception that health visitor advice and support was poor. Earlier weaning was associated with a focus on the importance of putative weaning signs from the baby. Qualitative analysis revealed a number of conflicting influences on the decision about when to give solid foods: recommendations, guidelines and advice, signs from the baby, beliefs about solids and maternal considerations. The conflict that some mothers experience in deciding when to give their babies solid food between the rigid recommendations, more tailored guidance from health professionals and their perceptions of putative weaning signs from their infants poses a particular problem for those attempting to provide clear and helpful health education information. Future research must assess the extent to which this conflict is prevalent in the general population, and investigate the salience and utility of different health education messages to promote good infant health.